NCsoft's latest zone tour video for Aion: The Tower of Eternity ice, sand, lava, forests, and 50% more heim than any other massively multiplayer online role-playing zone.
Having not actually played Aion I don't suppose I can really comment on the heim levels of any particular zone, but people don't generally name online game zones ironically. Everquest's Everfrost is permanently frozen. World of Warcraft's Burning Lands are technically burning. You don't name a zone Morheim unless there's an abundant supply of heim nearby.